1. Field of the Invention
This invention relates to a portable computer powered by rechargeable batteries, and more particularly to the method of charging and switching individual batteries and indicating battery state in a portable computer.
2. Description of the Related Art
Computers powered by detachable batteries have been developed. In this type of computer, the operator cannot tell whether or not batteries are in the computer unless he checks the battery compartment. Thus, an operator may be unaware that only one battery is in a battery compartment that can hold more than one battery. The single battery will then run short earlier than expected, during operation, so that the computer is forced to stop operation half way. Such mishaps tend to occur with portable computers often powered by batteries only, such as lap-top computers or book-type (note-type) computers. These disadvantages of conventional portable computers prevent users from making full use of the easy-to-carry feature.
Computers with a low-battery indicator are also available. For rechargeable batteries, however, the low-battery indication cannot tell exactly the state of the battery. Further, it is impossible to predict the remaining battery capacity, the available computer operation time, and other factors unless it is known whether the batteries are fully charged or still being charged. Conventionally, however, there were no such computers that automatically detected the charged/discharged state of the rechargeable batteries, and then informed the operator of the results. Exact information on the charged/discharged state is very helpful in making full use of the features of portable computers often powered by batteries only.